This study looked at how glioma diagnoses changed when doctors used three different World Health Organization (WHO) classification systems from 2007, 2016, and 2021. The researchers reviewed records from 443 patients who had elective tumor surgery at a single center in Latin America between 2010 and 2024.
Under the 2007 criteria, glioblastoma was the most common tumor type, and almost all tumors were classified based on their appearance under a microscope. However, the study found that the proportion of tumors labeled as 'not otherwise specified' (NOS) or with incomplete characterization increased over time. Using the 2021 criteria, 24% of tumors were categorized as high- or low-grade glioma NOS.
The main reason to be careful is that this was a retrospective analysis from one center, and the authors noted limited access to molecular testing, which is now a key part of modern glioma diagnosis. The study does not report any safety concerns, as it focused on diagnostic accuracy, not treatment.
What readers should realistically take from this is that glioma classification is evolving, and newer systems may rely more on molecular information that was not available in this study. This research highlights the challenges in diagnosing brain tumors but does not change current medical practice.
